There has been no shortage of innovation in the consumer graphics card market for the last several generations of hardware. Programmable shaders, 256-bit memory interfaces and multiple processing pipelines are making for some high-performing and extremely efficient hardware.

Much of that, though, can take a back seat when it's time to break out the benchmarks and games. It's not the process that matters, but rather the results are what count. NVIDIA is hoping its means to the best end is through the revival of SLI technology, the ability to run two graphics cards in one machine.

Instead of the Scan Line Interleave from the 3dfx days, today's implementation is called Scalable Link Interface. Here's what NVIDIA has to say about its iteration of SLI:

How does this technology differ from 3dfx's SLI?

NVIDIA SLI differs in many ways. First, 3dfx SLI was implemented on a shared bus using PCI. The PCI bus delivered ~100MB/sec. of bus throughput, while PCI Express is a point-to-point interface that can deliver ~60 times the total bandwidth of PCI. Second, 3dfx SLI performed interleaving of scan lines, and combined in the analog domain, which could result in image quality issues due to DAC differences and other factors.

3dfx Voodoo technology also only performed triangle setup, leaving the geometry workload for the CPU, hence 3dfx SLI only scaled simple texture fill rate, and then used inter-frame scalability. NVIDIA SLI technology is PCI Express based, uses a completely digital frame combining method that has no impact on image quality, can scale geometry performance, and supports a variety of scalability algorithms to best match the scalability method with application demands.

Sure sounds good, doesn't it? I can't pretend to understand all of it, I just want to know if it works.

I decided to migrate my AMD Athlon 64 3500+ processor from an NVIDIA nForce3 Ultra AGP system to the nForce4 SLI chipset. My intention was to sell my motherboard and AGP GeForce 6800 GT, purchase the SLI board and one PCI-Express GeForce 6600 GT. We contacted MSI and they came through and provided a second GeForce 6600 GT. Thanks to a special at an online retailer, here's what I ended up purchasing.

The Packages

Not only was the MSI motherboard on sale, I had good luck with my previous K8N Neo2 Platinum. I also went with the MSI video card because it was among the least expensive GeForce 6600 GT cards available. The value was made even more appealing due to the video card's rather large software bundle.

In the Video Card Box

To quote Super Troopers, one of my favorite movies, "That's a lotta hooch!" Not only is there a comprehensive set of applications, including DVD playback and virtual CD-ROM drive software, you get two pretty decent full-version games: Prince of Persia: Sands of Time and XIII. In the interest of wanting to review this video card's SLI capabilities in a timely fashion, MSI Computer Corp. provided me with a matching 6600 GT.

Twin Killing

While the red PCB looks cool, the actual cooling setup was what attracted me to this particular card. A copper cooler that also covers the video memory is something that should prove to be beneficial for the card's long-term health. The 6600 GT in PCI-Express form does not require additional connections directly to my system power supply, even when running in an SLI configuration. Speaking of configurations, let's check out the other hardware and driver software that will propel this duo.